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![Eric Eastwood](/assets/img/avatar_default.png)
Process previously failed backfill events in the background because they are bound to fail again and we don't need to waste time holding up the request for something that is bound to fail again. Fix https://github.com/matrix-org/synapse/issues/13623 Follow-up to https://github.com/matrix-org/synapse/issues/13621 and https://github.com/matrix-org/synapse/issues/13622 Part of making `/messages` faster: https://github.com/matrix-org/synapse/issues/13356
138 lines
3.9 KiB
Python
138 lines
3.9 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2020 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import heapq
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from itertools import islice
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from typing import (
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Callable,
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Collection,
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Dict,
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Generator,
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Iterable,
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Iterator,
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List,
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Mapping,
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Set,
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Sized,
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Tuple,
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TypeVar,
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)
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from typing_extensions import Protocol
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T = TypeVar("T")
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S = TypeVar("S", bound="_SelfSlice")
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class _SelfSlice(Sized, Protocol):
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"""A helper protocol that matches types where taking a slice results in the
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same type being returned.
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This is more specific than `Sequence`, which allows another `Sequence` to be
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returned.
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"""
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def __getitem__(self: S, i: slice) -> S:
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...
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def batch_iter(iterable: Iterable[T], size: int) -> Iterator[Tuple[T, ...]]:
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"""batch an iterable up into tuples with a maximum size
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Args:
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iterable: the iterable to slice
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size: the maximum batch size
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Returns:
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an iterator over the chunks
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"""
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# make sure we can deal with iterables like lists too
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sourceiter = iter(iterable)
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# call islice until it returns an empty tuple
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return iter(lambda: tuple(islice(sourceiter, size)), ())
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def chunk_seq(iseq: S, maxlen: int) -> Iterator[S]:
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"""Split the given sequence into chunks of the given size
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The last chunk may be shorter than the given size.
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If the input is empty, no chunks are returned.
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"""
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return (iseq[i : i + maxlen] for i in range(0, len(iseq), maxlen))
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def partition(
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iterable: Iterable[T], predicate: Callable[[T], bool]
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) -> Tuple[List[T], List[T]]:
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"""
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Separate a given iterable into two lists based on the result of a predicate function.
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Args:
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iterable: the iterable to partition (separate)
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predicate: a function that takes an item from the iterable and returns a boolean
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Returns:
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A tuple of two lists, the first containing all items for which the predicate
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returned True, the second containing all items for which the predicate returned
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False
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"""
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true_results = []
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false_results = []
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for item in iterable:
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if predicate(item):
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true_results.append(item)
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else:
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false_results.append(item)
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return true_results, false_results
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def sorted_topologically(
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nodes: Iterable[T],
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graph: Mapping[T, Collection[T]],
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) -> Generator[T, None, None]:
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"""Given a set of nodes and a graph, yield the nodes in toplogical order.
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For example `sorted_topologically([1, 2], {1: [2]})` will yield `2, 1`.
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"""
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# This is implemented by Kahn's algorithm.
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degree_map = {node: 0 for node in nodes}
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reverse_graph: Dict[T, Set[T]] = {}
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for node, edges in graph.items():
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if node not in degree_map:
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continue
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for edge in set(edges):
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if edge in degree_map:
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degree_map[node] += 1
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reverse_graph.setdefault(edge, set()).add(node)
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reverse_graph.setdefault(node, set())
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zero_degree = [node for node, degree in degree_map.items() if degree == 0]
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heapq.heapify(zero_degree)
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while zero_degree:
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node = heapq.heappop(zero_degree)
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yield node
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for edge in reverse_graph.get(node, []):
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if edge in degree_map:
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degree_map[edge] -= 1
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if degree_map[edge] == 0:
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heapq.heappush(zero_degree, edge)
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